Dawn is just breaking on June 5th at Djibouti's international airport, but it's already boiling hot on the tarmac. Mohammed Issa, a rotund and mustachioed border-police officer, gestures to a massive U.S. Air Force transport jet — a gray C-17 Globemaster — sitting a short distance away. "Since the start of the war in Yemen, it's been crazy here," he says. "Military flights, humanitarian aid — sometimes there's no space to park on the tarmac."

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Djibouti is a tiny state of citrus-colored shacks and goat-lined boulevards tucked into a barren, volcanic stretch of the Horn of Africa. It sits astride the narrow straits that lead to the Red Sea and the Suez Canal, and is home to the U.S.'s only permanent military base in Africa, Camp Lemonnier, linchpin of one of the Obama administration's most secretive and controversial programs: the drone-based campaign of surveillance and assassination against Al Qaeda and its allies in Somalia and Yemen.

Yemen, an impoverished, restive nation of 27 million on the southern end of the Arabian Peninsula has, in particular, been the focus of extensive counterterrorism efforts since the deadly attack on the USS Cole in 2000. Its branch of Al Qaeda has hatched some of the most dangerous plots against the United States, including the so-called Underwear Bomber, who tried to take down a commercial jet over Detroit with explosives in his boxer shorts. The Obama administration assassinated its first U.S. citizen, the fiery propagandist Anwar al-Awlaki, in Yemen's arid badlands. American special-operations forces have spent years training Yemeni counterterrorism units. In his speech unveiling his plan to combat ISIS last September, Obama held up Yemen as an example of where the U.S. had "successfully pursued" his counterterrorism strategy.

That strategy has now completely unraveled, as Yemen has become the latest country in the Middle East to descend into a full-fledged civil war. In March, after Houthi rebels seized control of the government, a coalition of Arab states led by Saudi Arabia, which accuses the Houthis of being supported by its archrival Iran, launched a U.S.-supported campaign of airstrikes and imposed a land, air and sea blockade of the country — which it says is necessary to keep out Iranian weapons.

Four months of bitter fighting later, the Houthis control even more territory. And the conflict has pushed this already impoverished country to the brink of a massive humanitarian catastrophe, with the aid community warning of an impending famine if the blockade is not lifted. More than 3,700 Yemenis have died, nearly half of them civilians, and more than 1.25 million have been displaced from their homes.

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Meanwhile, Al Qaeda has taken advantage of the chaos to seize wide swaths of eastern Yemen, including the port city of Mukalla, and has called for new attacks against the U.S. ISIS has gained a foothold and launched car-bomb attacks in the capital. Forced to evacuate its embassy and 125 special-operations advisers, the U.S. found its counterterrorism strategy in shambles, with many of the weapons and equipment it supplied to Yemen reported to be in the hands of militias.

"The coalition campaign in Yemen has devastating consequences for the U.S. counterterrorism strategy," says April Longley Alley, an analyst with the International Crisis Group. "They can continue to whack-a-mole with drone strikes, but the threat has become much deeper and more complicated over the long term."

Since the beginning of the war, Saudi Arabia has been preventing journalists from boarding the few humanitarian flights and ships it allows into Yemen, which is otherwise cut off from the world by the coalition blockade. I arrive in Djibouti in the hopes of finding a refugee or cargo boat that could take me there, but the news is bad. The Djiboutian government, I'm told, at the behest of the Saudi coalition, has recently started vetting even small commercial vessels. If my photographer and I want to get in by sea, we will have to find a smuggler willing to run the naval blockade in a speedboat.

The boat we find is 23 feet long and made of fiberglass, with a low, dagger-shaped hull, and looks a little flimsy for a 130-mile crossing of the Bab al Mandab strait. As we leave the port, an American military speedboat loops by to take a look at us, and my photographer and I slouch below the low gunwales. Once we are out to sea, our captain, whom I'll call Yousuf, relaxes. Like many of the fishermen who plied the coastal waters of the Horn of Africa, he is used to taking unusual cargo. In past years, he has taken Ethiopian migrants, crammed in 30 or more at a time, on this route and deposited them clandestinely on the Yemeni shore, to continue their harrowing journey in search of work in the wealthy petro-monarchies of the Persian Gulf. "They don't know enough to be afraid," he says.

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Over the horizon to our starboard is the port of Aden, which had once been the capital of an independent South Yemen, before the nation was reunited in 1990 under Ali Abdullah Saleh. Saleh had been a key U.S. ally and had supported the drone program in return for aid, but he was toppled in 2011 by protests during the Arab Spring, by demonstrators who demanded the same things as those in Cairo and Damascus: an end to economic stagnation and corruption, and the unaccountable, repressive institutions that sustained the region's strongmen.

For a moment, Yemen seemed like an Arab Spring success story. Saleh's relatively peaceful departure was brokered by the U.N., Saudi Arabia and the Gulf Cooperation Council. In the aftermath of the agreement, Saleh's vice president, Abdu Rabbu Mansur Hadi, ran unopposed for president and won. But the hopes of 2011 gradually faded as the country's political elites dallied and squabbled in the capital, Sana'a. Under Hadi's ineffectual reign, corruption and the economy worsened.

Meanwhile, the Houthis, a band of militia fighters based in the northern province of Saada, grew more and more powerful. Over the past few years, as Yemen's political order collapsed from infighting, the Houthis expanded their territory through a combination of political bargains and military victories, entering Sana'a last September and finally putting Hadi under house arrest in January. The next month, he escaped to Aden, where, backed by Saudi funding and weapons, he declared a new temporary capital. The Houthis marched into the south, Hadi fled to Riyadh, and the Saudi-led bombing campaign and blockade began.

As night falls, the boat's passage kicks up a glowing trail of phosphorescent algae in the dark and muggy sea. Yousuf can still navigate using the lights of the shoreline, but it doesn't seem wise to try to enter the rebel-held port at night in the middle of a civil war. We decide to anchor in the lee of a small island, and we bob gently for a few hours, watching a distant lighted procession of tankers and container ships steaming through the channel toward the Suez Canal.

Near dawn, we weigh anchor and set off again through choppy seas. The rising sun is obscured by a scrim of haze hanging over the highlands to the east as we approach the small port city of Mokha. The driver of a passing skiff smuggling gasoline has warned us there were airstrikes the night before, but we find a scene of calm activity at the pier. Teenage-looking Houthi fighters with battered Kalashnikovs take us to a weary but friendly civil servant; with assent, he stamps our passports and welcomes us to Yemen.

Our fixer has come down from Sana'a to pick us up, and we begin the long journey north to the capital in the mountains. There is a fuel shortage because of the blockade, and the highways are empty of traffic. In the port of Hodeidah, the breakdown in public services is apparent as we drive through puddles of raw sewage and around mounds of trash piled high in the roundabouts. There has been little or no electricity for months, and in the sweltering June nights, people have taken to sleeping in the streets, where they risk catching dengue fever from the mosquitoes — a major outbreak of the virus has hit coastal Yemen, with more than 8,000 cases reported in Aden alone.

It is night by the time we reach Sana'a. The capital lies in a bowl of mountains at more than 7,000 feet, and is one of the oldest continuously inhabited cities on Earth. In the age of camel caravans, it was a trading entrepôt between West and East, and was famous for the rich incenses and perfumes coveted in the temples of ancient Rome. Yemen's diaspora of merchants has spread around Africa and Asia, including the construction magnate Mohammed bin Laden, whose son Osama would be raised in his adopted homeland of Saudi Arabia.

In happier times, Yemen's warm, traditional society has been a magnet for adventure-minded tourists, and its fanciful old cities, whose multistory mud houses have been dubbed the "world's first skyscrapers," are UNESCO-listed World Heritage Sites. Now, however, blockaded and bombarded, the capital was in utter darkness, broken only by our headlights and the lamps wielded by Houthi fighters at checkpoints.

Saudi Arabia and Yemen might be likened to the U.S. and Mexico. Deep economic and cultural ties between the two countries have been strained by smuggling and illegal immigration, even as Saudi Arabia is home to a substantial population of Yemeni workers. And like the U.S. in Latin America, Saudi Arabia has always envisioned a right to intervene in the internal affairs of its poorer southern neighbor, based on its own national security. Though there is little evidence of direct Iranian military support for the Houthis, Saudi Arabia's Sunni monarchy has been increasingly concerned with a perceived Shiite threat from Iran, especially in the wake of its successful nuclear negotiations with the U.S.

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"This war overall has less to do with Yemen and more to do with Saudi Arabia's obsession with Iran's rise in the region," says Farea al-Muslimi, a Yemeni political analyst and a visiting scholar at the Carnegie Middle East Center. "It has to do with a regional message, especially from the Saudis to the U.S.: We don't need you, we can take the lead in our own war."

On March 25th, the Saudis launched Operation Decisive Storm. Its name wasn't the only thing that seemed torn from a Bush-era playbook. They had assembled a coalition of the willing, which included the wealthy Gulf states of the United Arab Emirates, Qatar and Bahrain — who, like the Saudis, were flush with U.S. and Western military equipment — as well as Egypt and unlikelier add-ons like Sudan and Morocco. The coalition contributed a handful of aircraft, but the majority was from the Saudi air force.

The Saudis' goal had been to force the Houthis to withdraw from Sana'a and return Hadi to power, but it was unclear how air power alone would achieve that, as the rebels continued their advance across the country, pushing into oil-rich Marib Province and capturing Al Anad air base, where U.S. special forces had been stationed. On April 21st, the Saudi military declared that Decisive Storm's mission had been accomplished, claiming that the threat from ballistic missiles and heavy weapons captured by the Houthis had been neutralized. (On June 6th, the Houthis fired their first Scud missile at Saudi Arabia.) Next, the Saudis launched Operation Renewal of Hope, whose objectives included "protecting civilians."

Meanwhile, the bombing and fighting across Yemen escalated. On an almost daily basis, the rumble of jets filled the air above Sana'a. Houthi anti-aircraft gunners would start firing — the jets flew so high that it was unclear what they were hoping to accomplish, and their shells would often land and cause casualties in the city — followed by the heavy explosions of airstrikes. The bombing did succeed in destroying much of Yemen's military and government infrastructure that the Houthis had captured. The Yemeni air force was wiped out, and the results of the U.S.'s train-and-equip program — worth $500 million since 2007 — vanished as security forces abandoned their posts or joined warring militias. On May 27th, the Saudis flattened the Special Security Force base in Sana'a, which had been home to the U.S.-funded and -trained Counterterrorism Unit.

By the time we arrive, however, the Saudis have been targeting individual houses in and around the densely packed capital, which, no matter how exact American precision-guided technology might be, leads inevitably to civilian death. In one early-morning strike against the house of one of President Saleh's relatives that I visited on June 13th, five members of a single family were killed when one of the bombs overshot its target by 20 feet and landed in front of their home.

In the historical old city of Sana'a, civilians, local response teams and Houthi fighters clear the rubble of four houses that were destroyed by what witnesses described as a missile or bomb from a Saudi Arabian warplane on June 12th, 2015.Sebastiano Tomada/Getty Reportage

As a result of the conflict, Yemen was splitting into north and south. Even as the Houthis consolidated their grip on Sana'a, by mid-July Saudi-backed Yemeni militiamen and armored vehicles from the Emirates had helped pro-Hadi forces establish a foothold in Aden. On July 16th, a delegation of exiled ministers flew back to the shattered southern city to prepare to establish a rival capital.

Meanwhile, as civilian casualties mount and Al Qaeda thrives on the chaos, the Obama administration is facing a dilemma of its own. American officials have warned that the U.S. counterterrorism strategy has suffered a setback in Yemen. "Al Qaeda is controlling an important port city, and their safe haven is unmolested by coalition airstrikes," says Alley of the Crisis Group. "It's quite clear that in many Western governments, there's a growing discomfort with the war."

For now, the American government continues to support the campaign by providing aerial refueling, intelligence support and targeting assistance. Four of the wealthy Gulf states involved — Saudi Arabia, Qatar, Bahrain and the UAE — are home to key U.S. military bases and are participating in the campaign against ISIS in Iraq and Syria. "For the U.S., Yemen is just not that important, especially when you have bigger issues like wrapping up the Iranian nuclear negotiations," says Alley. "The Saudis have brought significant weight to bear on pressuring their allies to support them. Why cross them and create tension?"

Since the Houthis took over Sana'a, their five-line slogan has become ubiquitous, affixed at checkpoints and chanted at noisy political rallies:

God is great

Death to America

Death to Israel

A curse upon the Jews

Victory to Islam

With their echo of the Iranian revolutionaries' infamous battle cry, the Houthis — who call themselves Ansar Allah, or Partisans of God — have presented an increasingly vexing enigma to the United States. They are often portrayed as a sectarian Shiite militia and combatants in a larger proxy war between Iran and Saudi Arabia that's taking place in Iraq and Syria. In an op-ed in The New York Times in April, Hadi, the exiled Saudi-backed president, warned that the Houthis were "puppets of the Iranian government," a threat to the region's shipping lanes and "destined to become the next Hezbollah."

In Western media, the conflict has been cast in sectarian tones, with the shorthand reference, as the same newspaper's editorial board put it in early July, to "an indigenous Shiite group allied with Iran." The truth is far more complex and grounded in Yemen's highly diverse society and tangled politics. For example, the Houthis are actually Zaydi Shiites, which is a different sect from Iranian Twelver Shiism, and closer in doctrine and tradition to Yemen's Sunni majority.

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At a hotel in downtown Sana'a, I meet with Mohammed al-Bukhaiti, a senior Houthi official and member of Ansar Allah's political committee. A short, broad-shouldered man with close-cropped stubble, Bukhaiti moves around the capital with a Kalashnikov and two bodyguards. A longtime political activist against Saleh's regime, he had spent years in exile in Canada and is quick to reminisce about its fast-food chains and friendly people. He is unapologetic, though, about Ansar Allah's anti-American ideology, which holds U.S. imperialism responsible for much of the Middle East's troubles. "Look what happened in Afghanistan, Iraq, Syria and now Yemen," he says. "Wherever there is U.S. interference, there is Al Qaeda and ISIS. It's to their advantage."

The Houthis' philosophy both looks back to Islam's original Sunni-Shia schism in the seventh century A.D. and forward to a contemporary global opposition to U.S. dominance that includes an admiration for Latin American leftism. "We should repeat the experience of the people of South America," he says. "They enlightened themselves about the danger of American policy."

When I point out that Ansar Allah's slogan is anti-Semitic, Bukhaiti insists that they are not against Jews as a people, but Israel's treatment of Palestinians. "If we were around during the time of the Nazis, we would support the Jews," he says.

The mixture of Islamism and Che Guevara is clearly influenced by the radical ideology of the Iranian Revolution, and Ansar Allah has warm relations with Iran and the other militant groups it supports, as Bukhaiti openly acknowledges. "Iran, Hamas, Hezbollah — what unites us is that we are against American imperialism. It's not something that we hide. We're proud of it." But he denies that they receive material support from Iran, or are in any way indebted to them: "We will never allow Iran to come here and use Yemen against any other country."

The Houthis are not a monolithic group, and during the National Dialogue Conference in 2013, which was supposed to determine Yemen's new political order, they advanced a surprisingly liberal agenda, one that supported limited women's rights and placed Islamic law as only one of the sources for legislation. But their critics see them returning to their core identity as a militia in response to the pressures of war, especially in the wake the assassinations of Houthi intellectuals like Ahmad Sharafeddin, killed on his way to the National Dialogue's final plenary session. "The problem is not that [the Houthi delegates] weren't genuine but that they were powerless," says the Carnegie Center's Muslimi.

The Houthis see themselves as the only party in Yemen that has been truly committed to and effective in battling Al Qaeda. Bukhaiti points out that both the former Saleh regime and the Saudis have had ambiguous relationships with Sunni jihadists, seeking to use them for their own ends. He tries to portray Ansar Allah's takeover as defensive in nature: "If we withdraw from the South now, Al Qaeda will fill the vacuum."

At their office in Sana'a, I visit Radyha al-Mutawakel and Abdulrasheed al-Faqih, a married couple who run Mwatana, one of the few independent and active human rights nongovernmental organizations in Yemen. They are both diminutive and gentle-mannered, and finish each other's sentences in their soft voices; they expect any day that Ansar Allah might arrest them or shut them down. Mwatana had documented the abuses that the Houthis had suffered under Saleh's counterinsurgency war; now, the tables are turned, with Amnesty International accusing the militia of torturing protesters in an attempt to suppress any opposition. "Once the Houthis took power, they became the main source of violations," says Mutawakel. "They are doing extrajudicial detentions and attacking media and civil society."

Since the start of the war, Ansar Allah has raided a number of media outlets and NGOs, particularly ones connected to its principal rival, the Yemeni branch of the Muslim Brotherhood. Opposing politicians have also been arrested and held without charge. Yemen's judicial system has largely broken down, and those detained by the Houthis lack any access to due process. "Anyone who speaks out against the Houthis, they take him," says Faqih. "The worst might be yet to come."

The main reason why Saudi Arabia views Yemen as such a vital strategic interest – and its Achilles' heel — is the 1,100-mile border between the two countries, which stretches over remote and mountainous terrain. Saada Province, on the Yemeni side, is the Houthis' traditional stronghold, and since the start of the war, fighting between Ansar Allah and the Saudi army has escalated. "They're a big challenge to the Saudis militarily," says Muslimi. "The Houthis have nothing to lose. They can send thousands of people to the borders to die."

The Saudis have responded by intensively bombing and shelling northern Yemen. On May 8th, in a move reminiscent of the U.S.'s "free-fire zones" in Vietnam, Saudi Arabia declared the cities of Sadaa and Marran to be "military targets" and reportedly dropped leaflets warning the entire civilian population to leave by 7 p.m. that evening.

Both Human Rights Watch and Amnesty International have accused Saudi Arabia of violating international humanitarian law. "The strikes killing civilians, in which there was no apparent military target, show at least a cruel indifference," says Belkis Wille of Human Rights Watch. "Bomb attacks that deliberately or recklessly targeted civilians would amount to war crimes." (A representative at the Saudi embassy in Washington, D.C., did not respond to a request for comment.)

Internally Displaced Persons (IDPs) fleeing the war find basic shelter in a temporary refugee camp bordering the town of Amran, Yemen, on June 15th, 2015.Sebastiano Tomada/Getty Reportage

Yet there was little news from Saada; no Western journalists had visited since the start of the war. Even the Red Cross had to temporarily abandon its office there. The only foreigners left were a medical team from Doctors Without Borders (also known by its French initials as MSF) that was holed up in a hospital in Saada City.

Getting there meant driving the highway 115 miles north from the capital, through arid mountains with bright-green irrigated valleys slashed through them. Saada has long been one of the most traditional parts of Yemen, and the villages here are built like fortresses from the mud they sit on, with three-story crenellated towers and slitted turrets that stand watch over verdant fields of khat, the popular local stimulant.

Once we reach the border of Saada Province, every few miles we encounter a charred hulk by the side of the road, or a massive crater that forces us to divert into the fields around it. Saudi jets have been targeting vehicles traveling the highway. Most of the recognizable wrecks are oil tankers or heavy trucks, but others are clearly ordinary vehicles — we pass a blasted flatbed with dozens of little dead goats scattered around it, and another damaged, abandoned pickup that is loaded with sacks of onions. The checkpoints here are mostly deserted — many bear damage from airstrikes — and the few vehicles we cross on the road are driving as fast as they can. From time to time, we can hear the rumble of a jet somewhere high above us.

When we arrive in Saada City, the devastation becomes apparent. On the deserted main road, two thin lanes have been cleared in the rubble and dust. On each side is a long stretch of shattered apartments and shops, their metal shutters crumpled like discarded tissue paper. Other buildings have been flattened by bomb strikes, their concrete floors pancaking down. We turn a corner and head into the old section of the city, where elaborate mud houses have been pulverized. Skirting a massive crater in front of the 1,200-year-old Imam al-Hadi mosque — it is deep enough to swallow a city bus — we pull into al-Jumhouri Hospital.

The hospital is a relative safe haven in Saada due to the presence of the MSF team, who had arrived in May. "They won't target us because of the foreigners," says Mohammad Hajjar, the hospital's director, a tall man with a permanently creased brow. When the bombing started, much of the hospital's staff fled, but Hajjar had remained behind with a small crew, bolstered by volunteers. Outside of the city, the public-health system in Saada has largely collapsed, with the U.N. rating Saada as the only province in Yemen that was "impossible or nearly impossible" to access.

The MSF team has set up two big overflow tents in the courtyard outside the ER; the week before we arrived, they had treated around 200 patients. "I've never seen what I've seen here," says Maria Green, an Argentine nurse who was the medical team's leader. She and her colleagues have been working nonstop since arriving and have barely slept from the constant airstrikes at night, some of them in close proximity to the compound. She has treated victims from the wars in Syria and the Central African Republic, but has found the results of modern air power shocking. "The kind of trauma you get from explosions — patients are coming in destroyed," she says, "and they all come at once."

The hospital is short on nearly everything, especially anesthetic. Even if they can get to Sana'a, medical supplies are drying up as the blockade wears on. For example, Hajjar tells me they have been surprised by a surge in snakebite victims; the bombings are so fierce that serpents swarm out of the ground, or else people encounter them when they flee their homes for the forest and caves. Hospital staff searched for antivenom in Sana'a but were able to find only five vials. "We are in a terrible situation," Hajjar says. "If the Saudis could blockade the air we breathe, they would." He says the hospital only has about 10 days of fuel left, and without it, its generators and intensive-care machines will stop. "We've had three fuel tankers try to deliver, and they've all been attacked on the road and destroyed," he says.

At the hospital, I meet Fatehi Betal, who is part of a local Houthi-affiliated civil council that is documenting the airstrikes. His family fled when the bombing started and their home had been reduced to rubble. A 24-year-old with rimless glasses and a tense expression that occasionally breaks into a youthful smile, Betal shows me the notes and photos that he has accumulated. According to his count, 341 civilians have been killed in the province since the start of the war. "Saada is different from other cities in Yemen," he says. "They target any gathering. We can't even pray in the mosque."

Leaving the safe confines of the hospital, Betal takes me on a macabre tour of the city's destruction. Saada's old souk, once packed with spice and textile sellers, is half-destroyed and empty except for stray dogs lying forlornly where the butcher shops had once been. We visit a car sales lot filled with charred wrecks, a blasted water bottling factory, and cratered restaurants and shopping plazas. Betal shows us the casing of a cluster bomb, and a half-exploded 1,000-pound bomb, both made in the U.S. The post office, central bank and cellphone network have been wiped out. Almost all the gas stations in Saada have been hit; at the Jarman station, there is a long line of incinerated vehicles. An airstrike had hit it while drivers were lined up for gasoline. "Nineteen people were killed, some burned beyond recongition," he says.

According to a U.N. satellite analysis, 1,171 structures in Saada City had been damaged or destroyed by airstrikes as of May 17th. The pattern of targets suggests that Saudi Arabia was focusing on Saada's infrastructure in an attempt to destroy its economy and flush out its civilian population.

I am told by the hospital staff that things are even worse in the rural border areas. The same day that we arrive at the hospital, there is news that there has been a strike in Radha, a remote village several hours away by road. Sure enough, that afternoon a procession of pickups screech into the hospital compound. The medical staff wheel up stretchers and pull bloodied figures out of the trucks. Soon there are bright-red spatters on the clean emergency-room floor as the hospital staff prepare patients for the operating theater. I ask a man leaning wearily against the back of a pickup, his clothes stained with his uncle's dried blood, what has happened.

A wounded civilian receives emergency medical treatment at the Doctors Without Borders hospital in Saada on June 15th, 2015.Sebastiano Tomada/Getty Reportage

"It was just after lunch, and people were leaving their houses," the man, Saleh Khairan, says. "There was a huge cluster bomb. We heard hundreds of explosions. They must have hit 50 houses, and at least one person from each house was killed or injured."

With gasoline so scarce, Khairan had been forced to pay a driver $350 to make the three-and-a-half-hour drive to Saada City, an expense the family can scarcely afford. "We're too poor to leave," he says. "There are no military bases near us or anything. This was the first time we've been attacked in this war, but they've been using cluster bombs in the surrounding areas."

We drive out to the village of Sabr, about a half-hour outside the city, where hospital officials have told us one of the worst civilian-casualty incidents had occurred. The countryside we pass through is lush — Saada is known as the fruit basket of Yemen — but the fields and mud houses we pass look deserted. "It's mostly shepherds left," says Betal.

Sabr was an austere cluster of mud homes, some of them elaborate three-story forts. Half of it had been reduced to churned rubble. Two older residents, dressed in long robes and shawls, join us and tell us what had happened.

On June 3rd, they say, an airstrike had hit several houses. Then, as the villagers worked to free victims from their collapsed homes, another wave of strikes had hit them. Betal arrived in an ambulance; he says the locals were hysterical and afraid to go back to try to rescue anyone. In all, they say, eight houses had been destroyed and 51 people killed. They produce a list of names with ages next to them — 36 of the victims were children. "These are their homes," Salem Ali says, pointing to the rubble. "My father's house is there." They claim there were no Houthi fighters or military targets in the village. "We don't know why they attacked us," he says.

It is impossible to verify their figures independently, but the MSF team confirm that there had been a large number of injured and killed who were brought to the hospital from the bombing in Sabr, their biggest incident to date, including eight children, many of them victims of asphyxiation or trauma from being trapped under the rubble.

As we speak, the recurring rumble of a Saudi jet grows louder and louder. It seems to be making circles over the valley, searching for targets. I imagine how we'd look from one of those infrared-camera videos they always play on TV: several pickup trucks full of men converge in a village and congregate together in some sort of meeting. Everyone looks suspicious as a ghostly infrared silhouette on those bomb-camera videos, and their evaporation in a white flash at the end feels justified and even satisfying.

The sound of the plane is excruciating. "I guess you must be used to hearing the sound of the jets all day," I say to the men, trying to sound lighthearted. "I'm not, so it really makes me nervous."

"Normally, we would run away when we hear it this close," Ali replies, "but you are here with us and we don't want to make you afraid."

Even before the war, many Yemenis lived in precarious poverty. About half the population lacked access to clean water, and the country imported 90 percent of its food from abroad. But the outbreak of heavy fighting, and in particular the blockade, has pushed them into a genuine humanitarian disaster. In June, the U.N. raised Yemen's crisis status to Category 3, its highest level, shared only by Syria, South Sudan and Iraq. And yet since the beginning of the conflict, the U.N. and the rest of the humanitarian community have struggled to deliver aid.

On our way back from Saada, we stop in Khamir, a small town set amid the rolling hills two hours north of the capital. Much of Saada's population has escaped to neighboring areas like this, part of a mass exodus of Yemeni civilians who have fled their homes and are desperately in need of assistance.

At the district hospital, I walk through the pediatric ward with Emmanuel Berbain, a French doctor who is part of a long-running MSF project here. In contrast to the mad urgency of the hospital in Saada, the ward has a funereal air, as black-robed, veiled mothers keep a silent vigil over the patients — there is nothing more somber than a roomful of silent children.

"Malnutrition is one of the side effects of the war and the blockade," Berbain says, examining a small boy who looks deflated from severe diarrhea. The influx of internally displaced persons, or IDPs, to Khamir means a surge in preventable illnesses: "Leishmaniasis, malaria, rickets."

In Yemen's traditional society, many IDPs are able to find shelter with their extended families, and others have been accommodated in government facilities like schools. Some, though, are simply on their own. Berbain and I jump into an MSF van and ride out to the edge of town, to an area known as the Khat Market, though it is just a series of barren, stepped fields overlooking the town. It is scattered with tents pitched on the open ground, some of them muddy old U.N. Refugee Agency shelters from past conflicts, others just tarps on sticks. "They basically have nothing. No food, no water," Berbain says. The U.N. hasn't shown up. A note of disbelief entered his voice. "There is no food distribution in all of Khamir." (A U.N. spokesman says food aid arrived in July.)

As we drove past one group of tents, Berbain tells the driver to stop, and he chats with a woman and asks if her child's itching had subsided yet. When we continued on, he pointed to some stray mutts lurking near the tents. "The dogs are shitting in the fields, and it spreads diseases," he explains. "Their child has ancylostomiasis." He makes a clawing motion against his chest: "It's worms moving under the skin."

As we tour the camp, Berbain is incredulous that the U.N. and the rest of the international humanitarian community are simply allowing people to die of starvation and exposure. "It's amazing. How is it possible that there can be so many IDPs without any response?" he says. "And it's getting worse every day."

International funding for aid has been slow to arrive to Yemen. When the U.N. issued a "flash appeal" for $274 million in aid in April, the Saudi government immediately pledged the entire amount. As of mid-July, none of the money had been delivered. "When the Saudis committed right off the bat, it made a lot of other donors relax the urgency on their contributions," says an official in charge of an international agency operating in Yemen. "Everyone's wondering if this is what the Saudis intended, or if they simply committed all the money without realizing they would not be in charge of where it went."

The biggest constraint on aid, however, remains the Saudi coalition's blockade of Yemen's airports, borders and shipping. Critics in the humanitarian community say it amounts to the collective punishment of an entire nation, and an example of siege warfare against civilian populations that is forbidden under international law. Saudi Arabia has disputed the term "blockade" and refers to the enforcement of a "restricted zone" and "controlled maritime area," whose purpose is to interdict Iranian weapons. While the coalition does allow some approved shipping into the country, the flow of essential goods has been strangled to a trickle. At the end of June, the U.N. estimated that Yemen was getting only 11 percent of its prewar fuel imports, and the gas shortage had drastically impeded aid delivery across the country.

The U.N. and the rest of the humanitarian community have been desperately pushing for a cease-fire, with little success. The U.N. special envoy, Ismail Ould Cheikh Ahmed, has been shuttling back and forth between Sana'a, Riyadh and Geneva, trying to kick-start peace negotiations that no one seems interested in. Both the Houthis and Hadi's government sent teams to Geneva in June for talks, but nothing came of it. And Ahmed was embarrassed in July when, a day after the announcement that he had brokered a cease-fire for the final week of Ramadan, Saudi jets continued bombing Yemen and the Houthis continued fighting on the ground. The Saudis said that they did not recognize the cease-fire.

Houthi supporters gather at the old gates of Sana'a protesting the Saudi Arabian coalition air strikes on June 14th, 2015.Sebastiano Tomada/Getty Reportage

During my visit, the question that I am most frequently asked by Yemenis is, "What do you think will happen to us?"

Yemen's Byzantine, fractious politics seem to confound even experienced observers. And yet, looking at what has already happened in Libya, Iraq and Syria, there seemed to be a precedent. Yemen's war will intensify. Rival sides will splinter into even smaller, more brutal militias. Regional powers will pour fuel on the fire in the pursuit of their own rivalries and domestic agendas, despite the risk of blowback. The international community will stand by helplessly. A massive human tragedy will unfold, shattering millions of lives and sending refugees into teeming camps and to the shores of an unwelcoming West. And a succession of increasingly nihilistic jihadist groups, the war's only winners, will thrive and pose a grave threat to the world.

"The world hasn't learned anything from the Syrian experience," Faqih, the human rights activist, tells me. "What's happening in Yemen is creating an environment that encourages jihadist groups. They have been dreaming of this day."

It may not be too late for Yemen. It may be that the genies of war and sectarian madness can somehow be put back in their bottles. If the U.S. can pressure Saudi Arabia and the coalition into ceasing the bombing and blockade, and in return the Houthis agree to stop their march on the rest of the country; if Saudi Arabia and Iran can be persuaded to leave Yemen out of their rivalry; and all sides within Yemen return to the table at Geneva — then maybe, just maybe, the country has a chance.

Faqih looks out the window. "I think the worst case is coming, without a miracle," he says, and chuckles bitterly. "And there are no miracles."

On the night before Ramadan begins — my last night in Yemen — a series of car bombs go off around Sana'a. Three hit mosques in the city, and another targets the offices of Ansar Allah's political committee. At the scene, I meet Bukhaiti, the Houthi leader I had interviewed, examining a hunk of twisted metal that had been a Hyundai Sonata. The bombings would soon be claimed by ISIS, but Bukhaiti isn't in the mood to make distinctions. "The Saudis, as well as Al Qaeda and ISIS — it's all the same," he says, his face made gaunt by the beam of a flashlight. "We're expecting that there will be more."